Amperage flags are used in some circuit breakers to indicate the amperage rating of a circuit breaker. The rating is typically printed on an exposed, visible surface of the flag that protrudes from an auxiliary cover of the circuit breaker. These flags must be visible from an exterior of the circuit breaker and also through the panelboard trim when installed into a panelboard. The auxiliary cover of the circuit breaker is also visible through an opening in the panelboard trim. The visible nature of the amperage flag allows visual inspection of the panelboard by an operator to ascertain the amperage rating of the circuit breaker by reading the rating printed on the amperage flag.
FIG. 1 illustrates an isometric view of a portion of a circuit breaker 100 that includes a conventional trip unit 102 that trips the circuit breaker 100 in response to detection of an electrical fault, such as a ground fault, a short circuit, and the like, breaking the electrical connection between the line current and the load to which the circuit breaker 100 is connected. Conventionally, a trip mechanism in the circuit breaker 100 operates a set of movable contacts that can interrupt electrical current flowing through the trip unit 102.
An amperage flag 106 is attached to a wall 116 of the trip unit 102 via an attachment member 114. A cutaway portion of an auxiliary cover 104 that houses components of the circuit breaker 100 is shown in phantom lines to show the amperage flag 106 in clear detail. The amperage flag 106 can include ribs to strengthen the attachment of the amperage flag 106 to the wall 116 of the trip unit 102.
When certain electrical faults occur, such as a short circuit that produces high electrical current, large arcs can be created generating high gas pressure inside the circuit breaker 100. The gas pressure expands in all directions, causing high stresses in the plastic housings of the circuit breaker 100.
During interruption of the current, the gas pressure pushes the trip unit 102 and the auxiliary cover 104 in opposite directions from one another, creating a stress point at the interface between the trip unit 102 and the auxiliary cover 104. As a result, the amperage flag 106 undesirably cracks or breaks at this interface, even with the stiffening ribs 112. The flag 106 can fall inside the circuit breaker 100 when it breaks, disappearing from view and potentially interfering with the operation of the circuit breaker. It would be desirable to have an amperage flag that does not crack or break (i.e., is non-frangible) during interruption of the circuit breaker.
During assembly of some circuit breakers, a hammer is installed in the trip unit. A solenoid activates this hammer in response to detection of an electrical fault, and the hammer rotates to engage a trip mechanism of the circuit breaker, which causes a sequence of mechanical actions to trip the circuit breaker by separating the movable contacts and severing the electrical connections between the circuit breaker and the loads being protected. During assembly of such circuit breakers, the hammer can pop out of its position in the trip unit. It would be desirable to provide a way of ensuring that the hammer stays in its pre-assembled position during assembly of the trip unit so that it does not pop out of that position.